Profile of Barbara Sherwood Lollar.

Barbara Sherwood Lollar tracked sustained hydrogen release from Earth’s crust nearly 2.4 kilometers under the Canadian Shield, enough to generate 4.7 million kilowatt-hours per year.

• Why it matters: Understanding how hydrogen and deep fluids persist in Earth’s crust helps constrain the long-term processes shaping geochemistry and the age of subsurface reservoirs.
• What they did: She revisited the Kidd Creek Mine in Ontario, Canada, using noble-gas studies to analyze waters flowing from deep fractures first explored in 2013.
• The result: Those waters were 1.6 billion years old, and the noble-gas–aided findings pushed the age of Earth’s oldest waters back by hundreds of millions of years.